Dual polarization optical modulator using dual broadband multi-electrode weighted direct analog phase modulators

a dual-polarization, analog phase modulator technology, applied in optics, instruments, optical light guides, etc., can solve the problems of low modulation efficiency per unit length, degrade the quality of constellation diagrams, and mismatch in frequency respons

Active Publication Date: 2014-10-28
LUMENTUM OPERATIONS LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0019]The present disclosure may solve the problem of mismatched S21 (e/o) frequency responses in direct analog phase modulators operating at high frequencies by using two or more interaction regions having diffe

Problems solved by technology

The mismatch in frequency response will degrade the quality of the constellation diagram in FIG. 2 because the I and Q e/o responses will not match for different digital data bit sequences having different electrical spectral content.
They do not teach how to modulator light within a waveguide using more than one signal electrode, nor do they teach how to match the frequency responses corresponding to different signal electrodes.
In U.S. Pat.

Method used

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  • Dual polarization optical modulator using dual broadband multi-electrode weighted direct analog phase modulators
  • Dual polarization optical modulator using dual broadband multi-electrode weighted direct analog phase modulators
  • Dual polarization optical modulator using dual broadband multi-electrode weighted direct analog phase modulators

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first embodiment

[0043]FIG. 5 illustrates the present disclosure comprising a three interaction section modulator from two staggered electrodes. RF signal electrode #1 206 has two interaction regions 206a that are before and after a single interaction region 208a for RF signal electrode #2 208. The sum of the first and third interaction regions, L1+L3, is twice that of the second interaction region of length L2 in order to achieve the 2:1 scaling ratio of modulation strengths. The third interaction region length, L3, is longer than the first, L1, to compensate for RF loss in the electrode. The difference in lengths of the first and third sections causes the center of the second section to be before the center of the entire structure. The lengths of the three sections, L1, L2, and L3, normalized to the total electrode length, are 0.309, 0.333, and 0.358, respectively. For this design, the I signal is applied to signal electrode #1 while the Q signal is applied to signal electrode #2.

[0044]In FIG. 5, ...

third embodiment

[0053]FIG. 11 illustrates the present disclosure where a six section modulator is formed from three staggered electrodes. An electro-optical phase modulator 400 comprises a waveguide 402 having an input end 401 and an output end 403 is formed in a single domain structure electro-optical substrate 404. Three signal electrodes 406,408 and 410 are provided on the substrate 404 forming shifting lines along the waveguide 402 from a first end proximate to the input 401 to a second end proximate to the output 403. Between the ends of each electrode 406, 408, 410 are a plurality of interaction lengths, shifted lengths and transition lengths. Using electrode 406 as an example, two interaction lengths 406a and four shifted lengths 406b are interspaced by five transition lengths 406c. The electrodes 406, 408 and 410 have a complimentary cascading structure that allows each of the three electrodes 406, 408, 410 to transition between interaction regions and alternate which electrode 406, 408, 41...

embodiment 500

[0091]FIG. 20 provides an enlarged view of an interaction region of the embodiment 500′ of FIG. 19. Specifically, interaction region IR1 of modulator 502 is illustrated in greater detail. As described in U.S. Pat. No. 7,701,630, the interaction region IR1 includes an interaction length that is split into several sections that alternate between modulating different waveguides with a pair of electrode polarity and domain inversion sections INVa and INVb. The interaction length 601 is divided into four sections 602, 604, 606 and 608. Sections 602 and 606 have unequal length and modulate the same waveguide branch 610. Sections 606 and 608 have unequal length and modulate the same waveguide branch 612. Transition sections 614 within the interaction length 601 displace the signal electrode between waveguide branches 610, 612.

[0092]Although the waveguides and electrode structures have been illustrated as straight lined structures, in some embodiments the waveguides and electrode structures...

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Abstract

An electro-optical phase modulator, dual polarization modulator applying that modulator and a phase modulation method are disclosed. A waveguide in an electro-optical substrate has at least two electrodes for modulating the waveguide. Each electrode receives a sequential bit of a precoded digital input and forms a shifting line from a first input end through interaction lengths near the waveguide causing modulation, shifted lengths distal from the waveguide for avoiding modulating the waveguide and transitions between these lengths by shifting the electrode away from or towards the waveguide. At least one electrode has a shorter interaction length closer to the input than a longer interaction length of the same electrode. Each electrode's modulation strength is proportional to its total interaction length, which doubles for each electrode, producing well matched S21 electro-optical responses from 10 kHz to 50 GHz, when shifted to account for the doubling.

Description

TECHNICAL FIELD[0001]The present invention relates to broadband electro-optical phase modulators and in particular, to well matched high frequency electro-optical phase modulators having multiple multi-sectioned electrodes for modulating a single waveguide without domain inversion.BACKGROUND OF THE INVENTION[0002]Electro-optical modulators modulate electrical signals onto a light beam in order to generate a modulated optical beam that carries data. Optical waveguide modulators are well known in the art and are used in a variety of applications.[0003]An electro-optical phase modulator according to the present disclosure may be useful in the prior art 100 G CFP modulator illustrated in FIG. 1. The 100 Gb / s small form factor device 100 consists of an input fiber 10 for receiving an optical signal 11 connected to a lithium niobate substrate 12 having a waveguide 14 with a y-branch 16 to split the optical signal onto two arms, each of which is modulated by phase modulators 18 having an I...

Claims

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Application Information

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IPC IPC(8): G02F1/03G02F1/035G02F1/35
CPCG02F1/0327G02F1/0322G02F1/0316G02F2201/122G02F1/225H04B10/50
Inventor KISSA, KARL
Owner LUMENTUM OPERATIONS LLC
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